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# Commit Procedures
## For external developers
See [Submitting Code to VTR](CONTRIBUTING.md#submitting-code-to-vtr).
## For developers with commit rights
The guiding principle in internal development is to submit your work into the repository without breaking other people's work.
When you commit, make sure that the repository compiles, that the flow runs, and that you did not clobber someone else's work.
In the event that you are responsible for "breaking the build", fix the build at top priority.
We have some guidelines in place to help catch most of these problems:
1. Before you push code to the central repository, your code MUST pass the check-in regression test.
The check-in regression test is a quick way to test if any part of the VTR flow is broken.
At a minimum you must run:
```shell
#From the VTR root directory
$ ./run_reg_test.pl vtr_reg_basic
```
You may push if all the tests return `All tests passed`.
However you are strongly encouraged to run both the *basic* and *strong* regression tests:
```shell
#From the VTR root directory
$ ./run_reg_test.pl vtr_reg_basic vtr_reg_strong
```
since it performs much more thorough testing.
It is typically a good idea to run tests regularily as you make changes.
If you have failures see [how to debugging failed tests](#debugging-failed-tests).
2. The automated [BuildBot](http://builds.verilogtorouting.org:8080/waterfall) will perform more extensive regressions tests and mark which revisions are stable.
3. Everyone who is doing development must write regression tests for major feature they create.
This ensures regression testing will detect if a feature is broken by someone (or yourself).
See [Adding Tests](#adding-tests) for details.
4. In the event a regression test is broken, the one responsible for having the test pass is in charge of determining:
* If there is a bug in the source code, in which case the source code needs to be updated to fix the bug, or
* If there is a problem with the test (perhaps the quality of the tool did in fact get better or perhaps there is a bug with the test itself), in which case the test needs to be updated to reflect the new changes.
If the golden results need to be updated and you are sure that the new golden results are better, use the command `../scripts/parse_vtr_task.pl -create_golden your_regression_test_name_here`
5. Keep in sync with the master branch as regularly as you can (i.e. `git pull` or `git pull --rebase`).
The longer code deviates from the trunk, the more painful it is to integrate back into the trunk.
Whatever system that we come up with will not be foolproof so be conscientious about how your changes will effect other developers.
# Code Formatting
Some parts of the VTR code base (e.g. VPR, libarchfpga, libvtrutil) have code formatting requirements which are checked automatically by regression tests.
If your code changes are not compliant with the formatting, you can run:
```shell
make format
```
from the root of the VTR source tree.
This will automatically reformat your code to be compliant with formatting requirements (this requires the `clang-format` tool to be available on your system).
## Large Scale Reformatting
For large scale reformatting (should only be performed by VTR maintainers) the script `dev/autoformat.py` can be used to reformat the code and commit it as 'VTR Robot', which keeps the revision history clearer and records metadata about reformatting commits (which allows `git hyper-blame` to skip such commits).
# Running Tests
VTR has a variety of tests which are used to check for correctness, performance and Quality of Result (QoR).
There are 4 main regression tests:
* `vtr_reg_basic`: ~1 minute serial
**Goal:** Fast functionality check
**Feature Coverage:** Low
**Benchmarks:** A few small and simple circuits
**Architectures:** A few simple architectures
This regression test is *not* suitable for evaluating QoR or performance.
It's primary purpose is to make sure the various tools do not crash/fail in the basic VTR flow.
QoR checks in this regression test are primarily 'canary' checks to catch gross degredations in QoR.
Ocassionally, code changes can cause QoR failures (e.g. due to CAD noise -- particularly on small benchmarks); usually such failures are not a concern if the QoR differences are small.
* `vtr_reg_strong`: ~20 minutes serial, ~15 minutes with `-j4`
**Goal:** Broad functionaly check
**Feature Coverage:** High
**Benchmarks:** A few small circuits, with some special benchmarks to exercise specific features
**Architectures:** A variety of architectures, including special architectures to exercise specific features
This regression test is *not* suitable for evaluating QoR or performance.
It's primary purpose is try and achieve high functionality coverage.
QoR checks in this regression test are primarily 'canary' checks to catch gross degredations in QoR.
Ocassionally, changes can cause QoR failures (e.g. due to CAD noise -- particularly on small benchmarks); usually such failures are not a concern if the QoR differences are small.
* `vtr_reg_nightly`: ~6 hours with `-j3`
**Goal:** Basic QoR and Performance evaluation.
**Feature Coverage:** Medium
**Benchmarks:** Small-medium size, diverse. Includes:
* MCNC20 benchmarks
* VTR benchmarks
* Titan 'other' benchmarks (smaller than Titan23)
**Architectures:** A wider variety of architectures
QoR checks in this regression are aimed at evaluating quality and run-time of the VTR flow.
As a result any QoR failures are a concern and should be investigated and understood.
* `vtr_reg_weekly`: ~42 hours with `-j4`
**Goal:** Full QoR and Performance evaluation.
**Feature Coverage:** Medium
**Benchmarks:** Medium-Large size, diverse. Includes:
* VTR benchmarks
* Titan23 benchmarks
**Architectures:** A wide variety of architectures
QoR checks in this regression are aimed at evaluating quality and run-time of the VTR flow.
As a result any QoR failures are a concern and should be investigated and understood.
These can be run with `run_reg_test.pl`:
```shell
#From the VTR root directory
$ ./run_reg_test.pl vtr_reg_basic
$ ./run_reg_test.pl vtr_reg_strong
```
The *nightly* and *weekly* regressions require the Titan benchmarks which can be integrated into your VTR tree with:
```shell
make get_titan_benchmarks
```
They can then be run using `run_reg_test.pl`:
```shell
$ ./run_reg_test.pl vtr_reg_nightly
$ ./run_reg_test.pl vtr_reg_weekly
```
To speed-up things up, individual sub-tests can be run in parallel using the `-j` option:
```shell
#Run up to 4 tests in parallel
$ ./run_reg_test.pl vtr_reg_strong -j4
```
You can also run multiple regression tests together:
```shell
#Run both the basic and strong regression, with up to 4 tests in parallel
$ ./run_reg_test.pl vtr_reg_basic vtr_reg_strong -j4
```
## Odin Functionality Tests
Odin has its own set of tests to verify the correctness of its synthesis results:
* `odin_reg_micro`: ~2 minutes serial
* `odin_reg_full`: ~6 minutes serial
These can be run with:
```shell
#From the VTR root directory
$ ./run_reg_test.pl odin_reg_micro
$ ./run_reg_test.pl odin_reg_full
```
and should be used when makeing changes to Odin.
## Unit Tests
VTR also has a limited set of unit tests, which can be run with:
```shell
#From the VTR root directory
$ make && make test
```
# Debugging Failed Tests
If a test fails you probably want to look at the log files to determine the cause.
Lets assume we have a failure in `vtr_reg_basic`:
```shell
#In the VTR root directory
$ ./run_reg_test.pl vtr_reg_strong
#Output trimmed...
regression_tests/vtr_reg_basic/basic_no_timing
-----------------------------------------
k4_N10_memSize16384_memData64/ch_intrinsics/common failed: vpr
k4_N10_memSize16384_memData64/diffeq1/common failed: vpr
#Output trimmed...
regression_tests/vtr_reg_basic/basic_no_timing...[Fail]
k4_N10_memSize16384_memData64.xml/ch_intrinsics.v vpr_status: golden = success result = exited
#Output trimmed...
Error: 10 tests failed!
```
Here we can see that `vpr` failed, which caused subsequent QoR failures (`[Fail]`), and resulted in 10 total errors.
To see the log files we need to find the run directory.
We can see from the output that the specific test which failed was `regression_tests/vtr_reg_basic/basic_no_timing`.
All the regression tests take place under `vtr_flow/tasks`, so the test directory is `vtr_flow/tasks/regression_tests/vtr_reg_basic/basic_no_timing`.
Lets move to that directory:
```shell
#From the VTR root directory
$ cd vtr_flow/tasks/regression_tests/vtr_reg_basic/basic_no_timing
$ ls
config run001 run003
latest run002 run004 run005
```
There we see there is a `config` directory (which defines the test), and a set of run-directories.
Each time a test is run it creates a new `runXXX` directory (where `XXX` is an incrementing number).
From the above we can tell that our last run was `run005` (the symbolic link `latest` also points to the most recent run directory).
From the output of `run_reg_test.pl` we know that one of the failing architecture/circuit/parameters combinations was `k4_N10_memSize16384_memData64/ch_intrinsics/common`.
Each architecture/circuit/parameter combination is run in its own sub-folder.
Lets move to that directory:
```shell
$ cd run005/k4_N10_memSize16384_memData64/ch_intrinsics/common
$ ls
abc.out k4_N10_memSize16384_memData64.xml qor_results.txt
ch_intrinsics.net odin.out thread_1.out
ch_intrinsics.place output.log vpr.out
ch_intrinsics.pre-vpr.blif output.txt vpr_stdout.log
ch_intrinsics.route parse_results.txt
```
Here we can see the individual log files produced by each tool (e.g. `vpr.out`), which we can use to guide our debugging.
We could also manually re-run the tools (e.g. with a debugger) using files in this directory.
# Evaluating Quality of Result (QoR) Changes
VTR uses highly tuned and optimized algorithms and data structures.
Changes which effect these can have significant impacts on the quality of VTR's design implementations (timing, area etc.) and VTR's run-time/memory usage.
Such changes need to be evaluated carefully before they are pushed/merged to ensure no quality degredation occurs.
If you are unsure of what level of QoR evaluation is neccessary for your changes, please ask a VTR developer for guidance.
## General QoR Evaluation Principles
The goal of performing a QoR evaluation is to measure precisely the impact of a set of code/architecture/benchmark changes on both the quality of VTR's design implemenation (i.e. the result of VTR's optimizations), and on tool run-time and memory usage.
This process is made more challenging by the fact that many of VTR's optimization algorithms are based on heuristics (some of which depend on randomization).
This means that VTR's implementation results are dependent upon:
* The initial conditions (e.g. input architecture & netlist, random number generator seed), and
* The precise optimization algorithms used.
The result is that a minor change to either of these can can make the measured QoR change.
This effect can be viewed as an intrinsic 'noise' or 'variance' to any QoR measurement for a particular architecture/benchmark/algorithm combination.
There are typically two key methods used to measure the 'true' QoR:
1. Averaging metrics accross multiple architectures and benchmark circuits.
2. Averaging metrics multiple runs of the same architecture and benchmark, but using different random number generator seeds
This is a further variance reduction technique, although it can be very CPU-time intensive.
A typical example would be to sweep an entire benchmark set accross 3 or 5 different seeds.
In practise any algorithm changes will likely cause improvements on some architecture/benchmark combinations, and degredations on others.
As a result we primarily focus on the *average* behaviour of a change to evaluate its impact.
However extreme outlier behaviour on particular circuits is also important, since it may indicate bugs or other unexpected behaviour.
### Key QoR Metrics
The following are key QoR metrics which should be used to evaluate the impact of changes in VTR.
Implementation Quality Metrics:
| Metric | Meaning | Sensitivity |
|-----------------------------|--------------------------------------------------------------------------|-------------|
| num_pre_packed_blocks | Number of primitive netlist blocks (after tech. mapping, before packing) | Low |
| num_post_packed_blocks | Number of Clustered Blocks (after packing) | Medium |
| device_grid_tiles | FPGA size in grid tiles | Low-Medium |
| min_chan_width | The minimum routable channel width | Medium\* |
| crit_path_routed_wirelength | The routed wirelength at the relaxed channel width | Medium |
| critical_path_delay | The critical path delay at the relaxed channel width | Medium-High |
\* By default, VPR attempts to find the minimum routable channel width; it then performs routing at a relaxed (e.g. 1.3x minimum) channel width. At minimum channel width routing congestion can distort the true timing/wirelength characteristics. Combined with the fact that most FPGA architectures are built with an abundance of routing, post-routing metrics are usually only evaluated at the relaxed channel width.
Run-time/Memory Usage Metrics:
| Metric | Meaning | Sensitivity |
|-----------------------------|---------------------------------------------------------------------------|-------------|
| vtr_flow_elapsed_time | Wall-clock time to complete the VTR flow | Low |
| pack_time | Wall-clock time VPR spent during packing | Low |
| place_time | Wall-clock time VPR spent during placement | Low |
| min_chan_width_route_time | Wall-clock time VPR spent during routing at the relaxed channel width | High\* |
| crit_path_route_time | Wall-clock time VPR spent during routing at the relaxed channel width | Low |
| max_vpr_mem | Maximum memory used by VPR (in kilobytes) | Low |
\* Note that the minimum channel width route time is chaotic and can be highly variable (e.g. 10x variation is not unusual). Minimum channel width routing performs a binary search to find the minimum channel width. Since route time is highly dependent on congestion, run-time is highly dependent on the precise channel widths searched (which may change due to perturbations).
In practise you will likely want to consider additional and more detailed metrics, particularly those directly related to the changes you are making.
For example, if your change related to hold-time optimization you would want to include hold-time related metrics such as `hold_TNS` (hold total negative slack) and `hold_WNS` (hold worst negative slack).
If your change related to packing, you would want to report additional packing-related metrics, such as the number of clusters formed by each block type (e.g. numbers of CLBs, RAMs, DSPs, IOs).
### Benchmark Selection
An important factor in performing any QoR evaluation is the benchmark set selected.
In order to draw reasonably general conclusions about the impact of a change we desire two characteristics of the benchmark set:
1. It includes a large number of benchmarks which are representative of the application domains of interest.
This ensures we don't over-tune to a specific benchmark or application domain.
2. It should include benchmarks of large sizes.
This ensures we can optimize and scale to large problem spaces.
In practise (for various reasons) satisfying both of these goals simultaneously is challenging.
The key goal here is to ensure the benchmark set is not unreasonably biased in some manner (e.g. benchmarks which are too small, benchmarks too skewed to a particular application domain).
### Fairly measuring tool run-time
Accurately and fairly measuring the run-time of computer programs is challenging in practise.
A variety of factors effect run-time including:
* Operating System
* System load (e.g. other programs running)
* Variance in hardware performance (e.g. different CPUs on different machines, CPU frequency scaling)
To make reasonably 'fair' run-time comparisons it is important to isolate the change as much as possible from other factors.
This involves keeping as much of the experimental environment identical as possible including:
1. Target benchmarks
2. Target architecture
3. Code base (e.g. VTR revision)
4. CAD parameters
5. Computer system (e.g. CPU model, CPU frequency/power scaling, OS version)
6. Compiler version
## Collecting QoR Measurements
The first step is to collect QoR metrics on your selected benchmark set.
You need at least two sets of QoR measurements:
1. The baseline QoR (i.e. unmodified VTR).
2. The modified QoR (i.e. VTR with your changes).
Note that it is important to generate both sets of QoR measurements on the same computing infrastructure to ensure a fair run-time comparison.
The following examples show how a single set of QoR measurements can be produced using the VTR flow infrastructure.
### Example: VTR Benchmarks QoR Measurement
The VTR benchmarks are a group of benchmark circuits distributed with the VTR project.
The are provided as synthesizable verilog and can be re-mapped to VTR supported architectures.
They consist mostly of small to medium sized circuits from a mix of application domains.
They are used primarily to evaluate the VTR's optimization quality in an architecture exploration/evaluation setting (e.g. determining minimum channel widths).
A typical approach to evaluating an algorithm change would be to run `vtr_reg_qor_chain` task from the nightly regression test:
```shell
#From the VTR root
$ cd vtr_flow/tasks
#Run the VTR benchmarks
$ ../scripts/run_vtr_task.pl regression_tests/vtr_reg_nightly/vtr_reg_qor_chain
#Several hours later... they complete
#Parse the results
$ ../scripts/parse_vtr_task.pl regression_tests/vtr_reg_nightly/vtr_reg_qor_chain
#The run directory should now contain a summary parse_results.txt file
$ head -5 vtr_reg_nightly/vtr_reg_qor_chain/latest/parse_results.txt
arch circuit script_params vpr_revision vpr_status error num_pre_packed_nets num_pre_packed_blocks num_post_packed_nets num_post_packed_blocks device_width device_height num_clb num_io num_outputs num_memoriesnum_mult placed_wirelength_est placed_CPD_est placed_setup_TNS_est placed_setup_WNS_est min_chan_width routed_wirelength min_chan_width_route_success_iteration crit_path_routed_wirelength crit_path_route_success_iteration critical_path_delay setup_TNS setup_WNS hold_TNS hold_WNS logic_block_area_total logic_block_area_used min_chan_width_routing_area_total min_chan_width_routing_area_per_tile crit_path_routing_area_total crit_path_routing_area_per_tile odin_synth_time abc_synth_time abc_cec_time abc_sec_time ace_time pack_time place_time min_chan_width_route_time crit_path_route_time vtr_flow_elapsed_time max_vpr_mem max_odin_mem max_abc_mem
k6_frac_N10_frac_chain_mem32K_40nm.xml bgm.v common 9f591f6-dirty success 26431 24575 14738 2258 53 53 1958 257 32 0 11 871090 18.5121 -13652.6 -18.5121 84 328781 32 297718 18 20.4406 -15027.8 -20.4406 0 0 1.70873e+08 1.09883e+08 1.63166e+07 5595.54 2.07456e+07 7114.41 11.16 1.03 -1 -1 -1 141.53 108.26 142.42 15.63 652.17 1329712 528868 146796
k6_frac_N10_frac_chain_mem32K_40nm.xml blob_merge.v common 9f591f6-dirty success 14163 11407 3445 700 30 30 564 36 100 0 0 113369 13.4111 -2338.12 -13.4111 64 80075 18 75615 23 15.3479 -2659.17 -15.3479 0 0 4.8774e+07 3.03962e+07 3.87092e+06 4301.02 4.83441e+06 5371.56 0.46 0.17 -1 -1 -1 67.89 11.30 47.60 3.48 198.58 307756 48148 58104
k6_frac_N10_frac_chain_mem32K_40nm.xml boundtop.v common 9f591f6-dirty success 1071 1141 595 389 13 13 55 142 192 0 0 5360 3.2524 -466.039 -3.2524 34 4534 15 3767 12 3.96224 -559.389 -3.96224 0 0 6.63067e+06 2.96417e+06 353000. 2088.76 434699. 2572.18 0.29 0.11 -1 -1 -1 2.55 0.82 2.10 0.15 7.24 87552 38484 37384
k6_frac_N10_frac_chain_mem32K_40nm.xml ch_intrinsics.v common 9f591f6-dirty success 363 493 270 247 10 10 17 99 130 1 0 1792 1.86527 -194.602 -1.86527 46 1562 13 1438 20 2.4542 -226.033 -2.4542 0 0 3.92691e+06 1.4642e+06 259806. 2598.06 333135. 3331.35 0.03 0.01 -1 -1 -1 0.46 0.31 0.94 0.09 2.59 62684 8672 32940
```
### Example: Titan Benchmarks QoR Measurements
The Titan benchmarks are a group of large benchmark circuits from a wide range of applications, which are compatible with the VTR project.
The are typically used as post-technology mapped netlists which have been pre-synthesized with Quartus.
They are substantially larger and more realistic than the VTR benchmarks, but can only target specificly compatible architectures.
They are used primarily to evaluate the optimization quality and scalability of VTR's CAD algorithms while targetting a fixed architecture (e.g. at a fixed channel width).
A typical approach to evaluating an algorithm change would be to run `vtr_reg_titan` task from the weekly regression test:
```shell
#From the VTR root
#Download and integrate the Titan benchmarks into the VTR source tree
$ make get_titan_benchmarks
#Move to the task directory
$ cd vtr_flow/tasks
#Run the VTR benchmarks
$ ../scripts/run_vtr_task.pl regression_tests/vtr_reg_weekly/vtr_reg_titan
#Several days later... they complete
#Parse the results
$ ../scripts/parse_vtr_task.pl regression_tests/vtr_reg_weekly/vtr_reg_titan
#The run directory should now contain a summary parse_results.txt file
$ head -5 vtr_reg_nightly/vtr_reg_qor_chain/latest/parse_results.txt
arch circuit vpr_revision vpr_status error num_pre_packed_nets num_pre_packed_blocks num_post_packed_nets num_post_packed_blocks device_width device_height num_clb num_io num_outputs num_memoriesnum_mult placed_wirelength_est placed_CPD_est placed_setup_TNS_est placed_setup_WNS_est routed_wirelength crit_path_route_success_iteration logic_block_area_total logic_block_area_used routing_area_total routing_area_per_tile critical_path_delay setup_TNS setup_WNS hold_TNS hold_WNS pack_time place_time crit_path_route_time max_vpr_mem max_odin_mem max_abc_mem
stratixiv_arch.timing.xml neuron_stratixiv_arch_timing.blif 0208312 success 119888 86875 51408 3370 128 95 -1 42 35 -1 -1 3985635 8.70971 -234032 -8.70971 1086419 20 0 0 2.66512e+08 21917.1 9.64877 -262034 -9.64877 0 0 127.92 218.48 259.96 5133800 -1 -1
stratixiv_arch.timing.xml sparcT1_core_stratixiv_arch_timing.blif 0208312 success 92813 91974 54564 4170 77 57 -1 173 137 -1 -1 3213593 7.87734 -534295 -7.87734 1527941 43 0 0 9.64428e+07 21973.8 9.06977 -625483 -9.06977 0 0 327.38 338.65 364.46 3690032 -1 -1
stratixiv_arch.timing.xml stereo_vision_stratixiv_arch_timing.blif 0208312 success 127088 94088 62912 3776 128 95 -1 326 681 -1 -1 4875541 8.77339 -166097 -8.77339 998408 16 0 0 2.66512e+08 21917.1 9.36528 -187552 -9.36528 0 0 110.03 214.16 189.83 5048580 -1 -1
stratixiv_arch.timing.xml cholesky_mc_stratixiv_arch_timing.blif 0208312 success 140214 108592 67410 5444 121 90 -1 111 151 -1 -1 5221059 8.16972 -454610 -8.16972 1518597 15 0 0 2.38657e+08 21915.3 9.34704 -531231 -9.34704 0 0 211.12 364.32 490.24 6356252 -1 -1
```
## Comparing QoR Measurements
Once you have two (or more) sets of QoR measurements they now need to be compared.
A general method is as follows:
1. Normalize all metrics to the values in the baseline measurements (this makes the relative changes easy to evaluate)
2. Produce tables for each set of QoR measurements showing the per-benchmark relative values for each metric
3. Calculate the GEOMEAN over all benchmarks for each normalized metric
4. Produce a summary table showing the Metric Geomeans for each set of QoR measurments
### QoR Comparison Gotchas
There are a variety of 'gotchas' you need to avoid to ensure fair comparisons:
* GEOMEAN's must be over the same set of benchmarks .
A common issue is that a benchmark failed to complete for some reason, and it's metric values are missing
* Run-times need to be collected on the same compute infrastructure at the same system load (ideally unloaded).
### Example QoR Comparison
Suppose we've make a change to VTR, and we now want to evaluate the change.
As described above we produce QoR measurements for both the VTR baseline, and our modified version.
We then have the following (hypothetical) QoR Metrics.
**Baseline QoR Metrics:**
| arch | circuit | num_pre_packed_blocks | num_post_packed_blocks | device_grid_tiles | min_chan_width | crit_path_routed_wirelength | critical_path_delay | vtr_flow_elapsed_time | pack_time | place_time | min_chan_width_route_time | crit_path_route_time | max_vpr_mem |
|----------------------------------------|--------------------|-----------------------|------------------------|-------------------|----------------|-----------------------------|---------------------|-----------------------|-----------|------------|---------------------------|----------------------|-------------|
| k6_frac_N10_frac_chain_mem32K_40nm.xml | bgm.v | 24575 | 2258 | 2809 | 84 | 297718 | 20.4406 | 652.17 | 141.53 | 108.26 | 142.42 | 15.63 | 1329712 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | blob_merge.v | 11407 | 700 | 900 | 64 | 75615 | 15.3479 | 198.58 | 67.89 | 11.3 | 47.6 | 3.48 | 307756 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | boundtop.v | 1141 | 389 | 169 | 34 | 3767 | 3.96224 | 7.24 | 2.55 | 0.82 | 2.1 | 0.15 | 87552 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | ch_intrinsics.v | 493 | 247 | 100 | 46 | 1438 | 2.4542 | 2.59 | 0.46 | 0.31 | 0.94 | 0.09 | 62684 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | diffeq1.v | 886 | 313 | 256 | 60 | 9624 | 17.9648 | 15.59 | 2.45 | 1.36 | 9.93 | 0.93 | 86524 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | diffeq2.v | 599 | 201 | 256 | 52 | 8928 | 13.7083 | 13.14 | 1.41 | 0.87 | 9.14 | 0.94 | 85760 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | LU8PEEng.v | 31396 | 2286 | 2916 | 100 | 348085 | 79.4512 | 1514.51 | 175.67 | 153.01 | 1009.08 | 45.47 | 1410872 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | LU32PEEng.v | 101542 | 7251 | 9216 | 158 | 1554942 | 80.062 | 28051.68 | 625.03 | 930.58 | 25050.73 | 251.87 | 4647936 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | mcml.v | 165809 | 6767 | 8649 | 128 | 1311825 | 51.1905 | 9088.1 | 524.8 | 742.85 | 4001.03 | 127.42 | 4999124 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | mkDelayWorker32B.v | 4145 | 1327 | 2500 | 38 | 30086 | 8.39902 | 65.54 | 7.73 | 15.39 | 26.19 | 3.23 | 804720 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | mkPktMerge.v | 1160 | 516 | 784 | 44 | 13370 | 4.4408 | 21.75 | 2.45 | 2.14 | 13.95 | 1.96 | 122872 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | mkSMAdapter4B.v | 2852 | 548 | 400 | 48 | 19274 | 5.26765 | 47.64 | 16.22 | 4.16 | 19.95 | 1.14 | 116012 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | or1200.v | 4530 | 1321 | 729 | 62 | 51633 | 9.67406 | 105.62 | 33.37 | 12.93 | 44.95 | 3.33 | 219376 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | raygentop.v | 2934 | 710 | 361 | 58 | 22045 | 5.14713 | 39.72 | 9.54 | 4.06 | 19.8 | 2.34 | 126056 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | sha.v | 3024 | 236 | 289 | 62 | 16653 | 10.0144 | 390.89 | 11.47 | 2.7 | 6.18 | 0.75 | 117612 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | stereovision0.v | 21801 | 1122 | 1156 | 58 | 64935 | 3.63177 | 82.74 | 20.45 | 15.49 | 24.5 | 2.6 | 411884 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | stereovision1.v | 19538 | 1096 | 1600 | 100 | 143517 | 5.61925 | 272.41 | 26.99 | 18.15 | 149.46 | 15.49 | 676844 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | stereovision2.v | 42078 | 2534 | 7396 | 134 | 650583 | 15.3151 | 3664.98 | 66.72 | 119.26 | 3388.7 | 62.6 | 3114880 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | stereovision3.v | 324 | 55 | 49 | 30 | 768 | 2.66429 | 2.25 | 0.75 | 0.2 | 0.57 | 0.05 | 61148 |
**Modified QoR Metrics:**
| arch | circuit | num_pre_packed_blocks | num_post_packed_blocks | device_grid_tiles | min_chan_width | crit_path_routed_wirelength | critical_path_delay | vtr_flow_elapsed_time | pack_time | place_time | min_chan_width_route_time | crit_path_route_time | max_vpr_mem |
|----------------------------------------|--------------------|-----------------------|------------------------|-------------------|----------------|-----------------------------|---------------------|-----------------------|-----------|------------|---------------------------|----------------------|-------------|
| k6_frac_N10_frac_chain_mem32K_40nm.xml | bgm.v | 24575 | 2193 | 2809 | 82 | 303891 | 20.414 | 642.01 | 70.09 | 113.58 | 198.09 | 16.27 | 1222072 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | blob_merge.v | 11407 | 684 | 900 | 72 | 77261 | 14.6676 | 178.16 | 34.31 | 13.38 | 57.89 | 3.35 | 281468 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | boundtop.v | 1141 | 369 | 169 | 40 | 3465 | 3.5255 | 4.48 | 1.13 | 0.7 | 0.9 | 0.17 | 82912 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | ch_intrinsics.v | 493 | 241 | 100 | 54 | 1424 | 2.50601 | 1.75 | 0.19 | 0.27 | 0.43 | 0.09 | 60796 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | diffeq1.v | 886 | 293 | 256 | 50 | 9972 | 17.3124 | 15.24 | 0.69 | 0.97 | 11.27 | 1.44 | 72204 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | diffeq2.v | 599 | 187 | 256 | 50 | 7621 | 13.1714 | 14.14 | 0.63 | 1.04 | 10.93 | 0.78 | 68900 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | LU8PEEng.v | 31396 | 2236 | 2916 | 98 | 349074 | 77.8611 | 1269.26 | 88.44 | 153.25 | 843.31 | 49.13 | 1319276 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | LU32PEEng.v | 101542 | 6933 | 9216 | 176 | 1700697 | 80.1368 | 28290.01 | 306.21 | 897.95 | 25668.4 | 278.74 | 4224048 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | mcml.v | 165809 | 6435 | 8649 | 124 | 1240060 | 45.6693 | 9384.4 | 296.99 | 686.27 | 4782.43 | 99.4 | 4370788 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | mkDelayWorker32B.v | 4145 | 1207 | 2500 | 36 | 33354 | 8.3986 | 53.94 | 3.85 | 14.75 | 19.53 | 2.95 | 785316 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | mkPktMerge.v | 1160 | 494 | 784 | 36 | 13881 | 4.57189 | 20.75 | 0.82 | 1.97 | 15.01 | 1.88 | 117636 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | mkSMAdapter4B.v | 2852 | 529 | 400 | 56 | 19817 | 5.21349 | 27.58 | 5.05 | 2.66 | 14.65 | 1.11 | 103060 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | or1200.v | 4530 | 1008 | 729 | 76 | 48034 | 8.70797 | 202.25 | 10.1 | 8.31 | 171.96 | 2.86 | 178712 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | raygentop.v | 2934 | 634 | 361 | 58 | 20799 | 5.04571 | 22.58 | 2.75 | 2.42 | 12.86 | 1.64 | 108116 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | sha.v | 3024 | 236 | 289 | 62 | 16052 | 10.5007 | 337.19 | 5.32 | 2.25 | 4.52 | 0.69 | 105948 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | stereovision0.v | 21801 | 1121 | 1156 | 58 | 70046 | 3.61684 | 86.5 | 9.5 | 15.02 | 41.81 | 2.59 | 376100 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | stereovision1.v | 19538 | 1080 | 1600 | 92 | 142805 | 6.02319 | 343.83 | 10.68 | 16.21 | 247.99 | 11.66 | 480352 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | stereovision2.v | 42078 | 2416 | 7396 | 124 | 646793 | 14.6606 | 5614.79 | 34.81 | 107.66 | 5383.58 | 62.27 | 2682976 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | stereovision3.v | 324 | 54 | 49 | 34 | 920 | 2.5281 | 1.55 | 0.31 | 0.14 | 0.43 | 0.05 | 63444 |
Based on these metrics we then calculate the following ratios and summary.
**QoR Metric Ratio** (Modified QoR / Baseline QoR):
| arch | circuit | num_pre_packed_blocks | num_post_packed_blocks | device_grid_tiles | min_chan_width | crit_path_routed_wirelength | critical_path_delay | vtr_flow_elapsed_time | pack_time | place_time | min_chan_width_route_time | crit_path_route_time | max_vpr_mem |
|----------------------------------------|--------------------|-----------------------|------------------------|-------------------|----------------|-----------------------------|---------------------|-----------------------|-----------|------------|---------------------------|----------------------|-------------|
| k6_frac_N10_frac_chain_mem32K_40nm.xml | bgm.v | 1.00 | 0.97 | 1.00 | 0.98 | 1.02 | 1.00 | 0.98 | 0.50 | 1.05 | 1.39 | 1.04 | 0.92 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | blob_merge.v | 1.00 | 0.98 | 1.00 | 1.13 | 1.02 | 0.96 | 0.90 | 0.51 | 1.18 | 1.22 | 0.96 | 0.91 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | boundtop.v | 1.00 | 0.95 | 1.00 | 1.18 | 0.92 | 0.89 | 0.62 | 0.44 | 0.85 | 0.43 | 1.13 | 0.95 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | ch_intrinsics.v | 1.00 | 0.98 | 1.00 | 1.17 | 0.99 | 1.02 | 0.68 | 0.41 | 0.87 | 0.46 | 1.00 | 0.97 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | diffeq1.v | 1.00 | 0.94 | 1.00 | 0.83 | 1.04 | 0.96 | 0.98 | 0.28 | 0.71 | 1.13 | 1.55 | 0.83 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | diffeq2.v | 1.00 | 0.93 | 1.00 | 0.96 | 0.85 | 0.96 | 1.08 | 0.45 | 1.20 | 1.20 | 0.83 | 0.80 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | LU8PEEng.v | 1.00 | 0.98 | 1.00 | 0.98 | 1.00 | 0.98 | 0.84 | 0.50 | 1.00 | 0.84 | 1.08 | 0.94 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | LU32PEEng.v | 1.00 | 0.96 | 1.00 | 1.11 | 1.09 | 1.00 | 1.01 | 0.49 | 0.96 | 1.02 | 1.11 | 0.91 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | mcml.v | 1.00 | 0.95 | 1.00 | 0.97 | 0.95 | 0.89 | 1.03 | 0.57 | 0.92 | 1.20 | 0.78 | 0.87 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | mkDelayWorker32B.v | 1.00 | 0.91 | 1.00 | 0.95 | 1.11 | 1.00 | 0.82 | 0.50 | 0.96 | 0.75 | 0.91 | 0.98 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | mkPktMerge.v | 1.00 | 0.96 | 1.00 | 0.82 | 1.04 | 1.03 | 0.95 | 0.33 | 0.92 | 1.08 | 0.96 | 0.96 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | mkSMAdapter4B.v | 1.00 | 0.97 | 1.00 | 1.17 | 1.03 | 0.99 | 0.58 | 0.31 | 0.64 | 0.73 | 0.97 | 0.89 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | or1200.v | 1.00 | 0.76 | 1.00 | 1.23 | 0.93 | 0.90 | 1.91 | 0.30 | 0.64 | 3.83 | 0.86 | 0.81 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | raygentop.v | 1.00 | 0.89 | 1.00 | 1.00 | 0.94 | 0.98 | 0.57 | 0.29 | 0.60 | 0.65 | 0.70 | 0.86 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | sha.v | 1.00 | 1.00 | 1.00 | 1.00 | 0.96 | 1.05 | 0.86 | 0.46 | 0.83 | 0.73 | 0.92 | 0.90 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | stereovision0.v | 1.00 | 1.00 | 1.00 | 1.00 | 1.08 | 1.00 | 1.05 | 0.46 | 0.97 | 1.71 | 1.00 | 0.91 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | stereovision1.v | 1.00 | 0.99 | 1.00 | 0.92 | 1.00 | 1.07 | 1.26 | 0.40 | 0.89 | 1.66 | 0.75 | 0.71 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | stereovision2.v | 1.00 | 0.95 | 1.00 | 0.93 | 0.99 | 0.96 | 1.53 | 0.52 | 0.90 | 1.59 | 0.99 | 0.86 |
| k6_frac_N10_frac_chain_mem32K_40nm.xml | stereovision3.v | 1.00 | 0.98 | 1.00 | 1.13 | 1.20 | 0.95 | 0.69 | 0.41 | 0.70 | 0.75 | 1.00 | 1.04 |
| | GEOMEAN | 1.00 | 0.95 | 1.00 | 1.02 | 1.01 | 0.98 | 0.92 | 0.42 | 0.87 | 1.03 | 0.96 | 0.89 |
**QoR Summary:**
| | baseline | modified |
|-----------------------------|----------|----------|
| num_pre_packed_blocks | 1.00 | 1.00 |
| num_post_packed_blocks | 1.00 | 0.95 |
| device_grid_tiles | 1.00 | 1.00 |
| min_chan_width | 1.00 | 1.02 |
| crit_path_routed_wirelength | 1.00 | 1.01 |
| critical_path_delay | 1.00 | 0.98 |
| vtr_flow_elapsed_time | 1.00 | 0.92 |
| pack_time | 1.00 | 0.42 |
| place_time | 1.00 | 0.87 |
| min_chan_width_route_time | 1.00 | 1.03 |
| crit_path_route_time | 1.00 | 0.96 |
| max_vpr_mem | 1.00 | 0.89 |
From the results we can see that our change, on average, achieved a small reduction in the number of logic blocks (0.95) in return for a 2% increase in minimum channel width and 1% increase in routed wirelength. From a run-time persepective the packer is substantially faster (0.42).
### Automated QoR Comparison Script
To automate some of the QoR comparison VTR includes a script to compare pares_resutls.txt files and generate a spreadsheet including the ratio and summary tables.
For example:
```shell
#From the VTR Root
$ ./vtr_flow/scripts/qor_compare.py parse_results1.txt parse_results2.txt parse_results3.txt -o comparison.xlsx
```
will produce ratio tables and a summary table for the files parse_results1.txt, parse_results2.txt and parse_results3.txt, where the first file (parse_results1.txt) is assumed to be the baseline used to produce normalized ratios.
# Adding Tests
Any time you add a feature to VTR you **must** add a test which exercies the feature.
This ensures that regression tests will detect if the feature breaks in the future.
Consider which regression test suite your test should be added to (see [Running Tests](#running-tests) descriptions).
Typically, test which exercise new features should be added to `vtr_reg_strong`.
These tests should use small benchmarks to ensure they:
* run quickly (so they get run often!), and
* are easier to debug.
If your test will take more than ~1 minute it should probably go in a longer running regression test (but see first if you can create a smaller testcase first).
## Adding a test to vtr_reg_strong
This describes adding a test to `vtr_reg_strong`, but the process is similar for the other regression tests.
1. Create a configuration file
First move to the vtr_reg_strong directory:
```shell
#From the VTR root directory
$ cd vtr_flow/tasks/regression_tests/vtr_reg_strong
$ ls
qor_geomean.txt strong_flyover_wires strong_pack_and_place
strong_analysis_only strong_fpu_hard_block_arch strong_power
strong_bounding_box strong_fracturable_luts strong_route_only
strong_breadth_first strong_func_formal_flow strong_scale_delay_budgets
strong_constant_outputs strong_func_formal_vpr strong_sweep_constant_outputs
strong_custom_grid strong_global_routing strong_timing
strong_custom_pin_locs strong_manual_annealing strong_titan
strong_custom_switch_block strong_mcnc strong_valgrind
strong_echo_files strong_minimax_budgets strong_verify_rr_graph
strong_fc_abs strong_multiclock task_list.txt
strong_fix_pins_pad_file strong_no_timing task_summary
strong_fix_pins_random strong_pack
```
Each folder (prefixed with `strong_` in this case) defines a task (sub-test).
Let's make a new task named `strong_mytest`.
An easy way is to copy an existing configuration file such as `strong_timing/config/config.txt`
```shell
$ mkdir -p strong_mytest/config
$ cp strong_timing/config/config.txt strong_mytest/config/.
```
You can now edit `strong_mytest/config/config.txt` to customize your test.
2. Generate golden reference results
Now we need to test our new test and generate 'golden' reference results.
These will be used to compare future runs of our test to detect any changes in behaviour (e.g. bugs).
From the VTR root, we move to the `vtr_flow/tasks` directory, and then run our new test:
```shell
#From the VTR root
$ cd vtr_flow/tasks
$ ../scripts/run_vtr_task.pl regression_tests/vtr_reg_strong/strong_mytest
regression_tests/vtr_reg_strong/strong_mytest
-----------------------------------------
Current time: Jan-25 06:51 PM. Expected runtime of next benchmark: Unknown
k6_frac_N10_mem32K_40nm/ch_intrinsics...OK
```
Next we can generate the golden reference results using `parse_vtr_task.pl` with the `-create_golden` option:
```shell
$ ../scripts/parse_vtr_task.pl regression_tests/vtr_reg_strong/strong_mytest -create_golden
```
And check that everything matches with `-check_golden`:
```shell
$ ../scripts/parse_vtr_task.pl regression_tests/vtr_reg_strong/strong_mytest -check_golden
regression_tests/vtr_reg_strong/strong_mytest...[Pass]
```
3. Add it to the task list
We now need to add our new `strong_mytest` task to the task list, so it is run whenever `vtr_reg_strong` is run.
We do this by adding the line `regression_tests/vtr_reg_strong/strong_mytest` to the end of `vtr_reg_strong`'s `task_list.txt`:
```shell
#From the VTR root directory
$ vim vtr_flow/tasks/regression_tests/vtr_reg_strong/task_list.txt
# Add a new line 'regression_tests/vtr_reg_strong/strong_mytest' to the end of the file
```
Now, when we run `vtr_reg_strong`:
```shell
#From the VTR root directory
$ ./run_reg_test.pl vtr_reg_strong
#Output trimmed...
regression_tests/vtr_reg_strong/strong_mytest
-----------------------------------------
#Output trimmed...
```
we see our test is run.
4. Commit the new test
Finally you need to commit your test:
```shell
#Add the config.txt and golden_results.txt for the test
$ git add vtr_flow/tasks/regression_tests/vtr_reg_strong/strong_mytest/
#Add the change to the task_list.txt
$ git add vtr_flow/tasks/regression_tests/vtr_reg_strong/task_list.txt
#Commit the changes, when pushed the test will automatically be picked up by BuildBot
$ git commit
```
# Debugging Aids
VTR has support for several additional tools/features to aid debugging.
## Sanitizers
VTR can be compiled using *sanitizers* which will detect invalid memory accesses, memory leaks and undefined behaviour (supported by both GCC and LLVM):
```shell
#From the VTR root directory
$ cmake -D VTR_ENABLE_SANITIZE=ON build
$ make
```
## Assertion Levels
VTR supports configurable assertion levels.
The default level (`2`) which turns on most assertions which don't cause significant run-time penalties.
This level can be increased:
```shell
#From the VTR root directory
$ cmake -D VTR_ASSERT_LEVEL=3 build
$ make
```
this turns on more extensive assertion checking and re-builds VTR.
# External Subtrees
VTR includes some code which is developed in external repositories, and is integrated into the VTR source tree using [git subtrees](https://www.atlassian.com/blog/git/alternatives-to-git-submodule-git-subtree).
To simplify the process of working with subtrees we use the [`dev/external_subtrees.py`](./dev/external_subtrees.py) script.
For instance, running `./dev/external_subtrees.py --list` from the VTR root it shows the subtrees:
```
Component: abc Path: abc URL: https://github.com/berkeley-abc/abc.git URL_Ref: master
Component: libargparse Path: libs/EXTERNAL/libargparse URL: https://github.com/kmurray/libargparse.git URL_Ref: master
Component: libblifparse Path: libs/EXTERNAL/libblifparse URL: https://github.com/kmurray/libblifparse.git URL_Ref: master
Component: libsdcparse Path: libs/EXTERNAL/libsdcparse URL: https://github.com/kmurray/libsdcparse.git URL_Ref: master
Component: libtatum Path: libs/EXTERNAL/libtatum URL: https://github.com/kmurray/tatum.git URL_Ref: master
```
Code included in VTR by subtrees should *not be modified within the VTR source tree*.
Instead changes should be made in the relevant up-stream repository, and then synced into the VTR tree.
### Updating an existing Subtree
1. From the VTR root run: `./dev/external_subtrees.py $SUBTREE_NAME`, where `$SUBTREE_NAME` is the name of an existing subtree.
For example to update the `libtatum` subtree:
```shell
./dev/external_subtrees.py --update libtatum
```
### Adding a new Subtree
To add a new external subtree to VTR do the following:
1. Add the subtree specification to `dev/subtree_config.xml`.
For example to add a subtree name `libfoo` from the `master` branch of `https://github.com/kmurray/libfoo.git` to `libs/EXTERNAL/libfoo` you would add:
```xml
<subtree
name="libfoo"
internal_path="libs/EXTERNAL/libfoo"
external_url="https://github.com/kmurray/libfoo.git"
default_external_ref="master"/>
```
within the existing `<subtrees>` tag.
Note that the internal_path directory should not already exist.
You can confirm it works by running: `dev/external_subtrees.py --list`:
```
Component: abc Path: abc URL: https://github.com/berkeley-abc/abc.git URL_Ref: master
Component: libargparse Path: libs/EXTERNAL/libargparse URL: https://github.com/kmurray/libargparse.git URL_Ref: master
Component: libblifparse Path: libs/EXTERNAL/libblifparse URL: https://github.com/kmurray/libblifparse.git URL_Ref: master
Component: libsdcparse Path: libs/EXTERNAL/libsdcparse URL: https://github.com/kmurray/libsdcparse.git URL_Ref: master
Component: libtatum Path: libs/EXTERNAL/libtatum URL: https://github.com/kmurray/tatum.git URL_Ref: master
Component: libfoo Path: libs/EXTERNAL/libfoo URL: https://github.com/kmurray/libfoo.git URL_Ref: master
```
which shows libfoo is now recognized.
2. Run `./dev/external_subtrees.py --update $SUBTREE_NAME` to add the subtree.
For the `libfoo` example above this would be:
```shell
./dev/external_subtrees.py --update libfoo
```
This will create two commits to the repository.
The first will squash all the upstream changes, the second will merge those changes into the current branch.
### Subtree Rational
VTR uses subtrees to allow easy tracking of upstream dependencies.
Their main advantages included:
* Works out-of-the-box: no actions needed post checkout to pull in dependencies (e.g. no `git submodule update --init --recursive`)
* Simplified upstream version tracking
* Potential for local changes (although in VTR we do not use this to make keeping in sync easier)
See [here](https://blogs.atlassian.com/2013/05/alternatives-to-git-submodule-git-subtree/) for a more detailed discussion.
# Finding Bugs with Coverity
[Coverity Scan](https://scan.coverity.com) is a static code analysis service which can be used to detect bugs.
### Browsing Defects
To view defects detected do the following:
1. Get a coverity scan account
Contact a project maintainer for an invitation.
2. Browse the existing defects through the coverity web interface
### Submitting a build
To submit a build to coverity do the following:
1. [Download](https://scan.coverity.com/download) the coverity build tool
2. Configure VTR to perform a *debug* build. This ensures that all assertions are enabled, without assertions coverity may report bugs that are gaurded against by assertions. We also set VTR asserts to the highest level.
```shell
#From the VTR root
mkdir -p build
cd build
CC=gcc CXX=g++ cmake -DCMAKE_BUILD_TYPE=debug -DVTR_ASSERT_LEVEL=3 ..
```
Note that we explicitly asked for gcc and g++, the coverity build tool defaults to these compilers, and may not like the default 'cc' or 'c++' (even if they are linked to gcc/g++).
3. Run the coverity build tool
```shell
#From the build directory where we ran cmake
cov-build --dir cov-int make -j8
```
4. Archive the output directory
```shell
tar -czvf vtr_coverity.tar.gz cov-int
```
5. Submit the archive through the coverity web interface
Once the build has been analyzed you can browse the latest results throught the coverity web interface
### No files emitted
If you get the following warning from cov-build:
[WARNING] No files were emitted.
You may need to configure coverity to 'know' about your compiler. For example:
```shell
cov-configure --compiler `which gcc-7`
```
On unix-like systems run `scan-build make` from the root VTR directory.
to output the html analysis to a specific folder, run `scan-build make -o /some/folder`
# Release Procedures
## General Principles
We periodically make 'official' VTR releases.
While we aim to keep the VTR master branch stable through-out development some users prefer to work of off an official release.
Historically this has coincided with the publishing of a paper detailing and carefully evaluating the changes from the previous VTR release.
This is particularly helpful for giving academics a named baseline version of VTR to which they can compare which has a known quality.
In preparation for a release it may make sense to produce 'release candidates' which when fully tested and evaluated (and after any bug fixes) become the official release.
## Checklist
The following outlines the procedure to following when making an official VTR release:
* Check the code compiles on the list of supported compilers
* Check that all regression tests pass
* Update regression test golden results to match the released version
* Increment the version number (set in root CMakeLists.txt)
* Create a new entry in the CHANGELOG.md for the release, summarizing at a high-level user-facing changes
* Create a git annotated tag (e.g. `v8.0.0`) and push it to github